DE60018931T3 - CONTINUOUS METHOD FOR EXTRUDING AND MECHANISM DISPERSING OF A POLYMER RESIN IN AN AQUEOUS OR NON-AQUEOUS MEDIUM - Google Patents

Description

The present invention relates to a continuous process for extruding and mechanically dispersing a polymeric resin in an aqueous or non-aqueous medium.

Stable aqueous dispersions of ionically charged polyepoxide-amine resins are known. Such resins are exemplified by McCollum et al. by doing U.S. Patent No. 5,114,552 described. McCollum et al. disclose that an organic polyepoxide can be made cationic by reaction with a primary or secondary amine in the presence of acid to form catalytically charged acid salt groups, or by reaction with tertiary amines to form quaternary ammonium salts. These resins are also crosslinkable due to incorporation of pendant hydroxyl groups or primary or secondary amine groups which are reactable with a protected polyisocyanate crosslinking agent. The crosslinked resin is dispersed in an acidified aqueous medium and the solid content is adjusted by the further addition of water. The extent of formation of cationic salts is preferably chosen to form a stable dispersion of the cationic polymer, although an external cationic surfactant may also be added. Such stable aqueous dispersions are useful as crosslinkable electrophoretic coating compositions.

The by McCollum et al. The preparation described is time consuming since it is carried out in a batch reactor. Further, the reaction requires significant amounts of organic solvent which must be removed afterwards.

The production of thermoplastic epoxy resins by continuous processes is known. For example, this describes U.S. Patent No. 4,612,156 the preparation of a high molecular weight phenoxy resin by mixing a diepoxy compound (eg, a diglycidyl ether of bisphenol A) with a difunctional compound (eg, bisphenol A) reactable with the epoxy groups in the presence of a catalyst and feeding the mixture through a single screw extruder or a pump in a twin-screw extruder to form an epoxy resin having a weight average molecular weight of about 30,000 daltons. Such a resin can be crushed and sieved and then dispersed in water in the presence of a surfactant to produce an aqueous dispersion (sometimes referred to as a powder slurry) suitable for coating applications.

It would be an improvement in the art if one could prepare a stable aqueous dispersion of resinous material in a continuous process, the resin coming directly from an extruder and not previously solidified and then crushed and sieved. It would be a further improvement in the art if crosslinkable electrophoretic coating dispersions could be prepared by a continuous process requiring little or no additional solvent.

• a) die kontinuierliche Phase im Wesentlichen unmischbar mit der dispersen Phase ist, und
• b) das Polymer selbstdispergierbar ist, und
• c) das Polymer fortlaufend in einem Extruder, der mit dem mechanischen Dispergator verbunden ist, extrudiert wird.

The present invention addresses the problems in the art by providing a continuous process for producing a stable dispersion or emulsion, the process comprising the step of mixing a stream of a molten or liquid disperse phase comprising a polymer and a stream a molten or liquid continuous phase, which is water or a polyether polyol, in a mechanical dispersing agent to form a dispersion or an emulsion, wherein

• a) the continuous phase is substantially immiscible with the disperse phase, and
• b) the polymer is self-dispersible, and
• c) the polymer is extruded continuously in an extruder connected to the mechanical disperser.

• a) kontinuierlichen Mischens des Stroms der flüssigen kontinuierlichen Phase bei einer Fließgeschwindigkeit R₁ und des Stroms der flüssigen dispersen Phase bei einer Fließgeschwindigkeit R₂ in dem Dispergator, und
• b) Mischens der gemischten Ströme im Wesentlichen in der Abwesenheit eines externen Tensids und bei einer im Wesentlichen konstanten Mischungsrate, um ohne Phasenumkehrung eine Emulsion mit einem hohen Anteil an innerer Phase zu erzeugen,

wobei der Strom der flüssigen dispersen Phase ein selbstdispergierbares Polymer oder Vorpolymer enthält und wobei R₂:R₁ dergestalt ist, dass die durchschnittliche Teilchengröße eines mittleren Volumens (mean volume average particle size, engl.) der Emulsion mit einem hohen Anteil an innerer Phase weniger als 2 μm beträgt oder die Polydispersität weniger als 2 beträgt.In a further aspect, the present invention relates to a method as described above, comprising the steps of;

• a) continuously mixing the flow of the liquid continuous phase at a flow rate R ₁ and the liquid disperse phase flow at a flow rate R ₂ in the dispersant, and
• b) mixing the mixed streams substantially in the absence of an external surfactant and at a substantially constant mixing rate to produce an emulsion having a high level of internal phase without phase inversion,

wherein the stream of liquid disperse phase contains a self-dispersible polymer or prepolymer, and wherein R ₂ : R _{1 is} such that the mean volume average particle size of the high internal phase emulsion is less is 2 μm or the polydispersity is less than 2.

The process of the present invention provides a means for producing a stable aqueous dispersion or emulsion by a continuous process comprising feeding an extruder with a continuous mechanical dispersion process is combined.

1 is a schematic representation of a preferred method according to the invention. A twin-screw extruder 20 will be in the order below with a gear pump 30 , a dispersant 40 , a first dilution mixer 50 and optionally a second dilution mixer 60 connected. Powdered or flaked resin is fed from a metering device 10 into an inlet 22 of the extruder 20 given in which the resin is melted or compounded.

The resin melt then becomes the gear pump 30 fed and with an initial stream of water passing through a pipe 42 in the disperser 40 flows, mixed. Surfactant may be added in addition to the water stream. After the streams are mixed, the water / resin dispersion is made using a dilution mixer 50 and optionally a second dilution mixer 60 diluted with additional water. Significantly, no water is added to the twin-screw extruder 20 however, water is added to the stream containing the molten resin after the melt has exited the extruder. In this way it will be in the extruder 20 eliminating the build up of vapor pressure.

Stable dispersions or emulsions can be prepared by mixing a stream of a molten or liquid disperse phase and a stream of a molten or liquid continuous phase in a mechanical dispersing agent to form a dispersion or emulsion. The molten or liquid disperse phase stream contains a polymer which is preferably solid at room temperature but molten at somewhat higher temperatures. The polymer is prepared in a molten state by a continuous process such as an extrusion process or a melt-kneading process, or first prepared and then melted. Examples of such extrusion processes include melt extrusion and compound extrusion.

In melt extrusion, a preformed polymer, generally in the form of flakes or pellets, is fed to an extruder to melt the polymer. The melt exits through the outlet port of the extruder and is passed through a heated tube, thus representing the flow of the molten polymer. This stream is combined with the stream of the continuous phase and finally with a mechanical dispersing agent. If it is desired to add fillers, stabilizers, pigments or other non-reactive compounds to the disperse phase stream, then the addition is advantageously carried out prior to extrusion and the components are mixed by means of coextrusion.

Examples of polymer resins include epoxy resins, poly (hydroxy amino ether) resins (PHAEs, as described in U.S. Pat U.S. Patent No. 5,834,078 polyurethane resins, polyurethane-urea resins, polyester resins, polyolefins, ethylene-acrylic acid copolymers or mixtures thereof or hybrids thereof, which polymers additionally contain ionic charges as described by McCollum et al. described, included. The polymers are due to the presence of ionic groups, potentially ionic groups, such as carboxylic acids and amines, or hydrophilic non-ionic groups, as in Markusch et al. by doing U.S. Patent No. 4,879,322 , Column 9, lines 61-68 and columns 10-12, self-dispersible. In some cases, it may be advantageous to disperse the resins substantially in the absence of an external surfactant. As used herein, the term "substantially in the absence means less than 0.1 percent of an external surfactant.

If necessary, an external surfactant may be added to a) the disperse phase, b) the continuous phase, or c) both phases. In general, it is preferred to use the surfactant upstream of the dispersant, more preferably through an inlet of the extruder, as in FIG 1 described to add to the disperse phase.

The molten or liquid continuous phase is water or a polyether polyol. The continuous phase and the disperse phase are substantially immiscible with each other so that stable dispersions or emulsions can be formed. An example of a dispersion containing a non-water-based continuous phase is ethylene-acrylic acid in a polyether polyol. The resin melt or resin liquid exiting the extruder forms the disperse phase stream which is mixed with the continuous phase stream and is then fed to a mechanical disperser. The ratio of the flow rate of the disperse phase flow (R ₂ ) to the flow rate of the continuous phase flow (R ₁ ) is advantageously adjusted to minimize the polydispersity and particle size of the stable aqueous dispersion. Guidance for the formation of low polydisperse stable emulsions and small particle size dispersions by a method of mixing a disperse phase containing stream with a continuous phase containing stream is provided by Pate et al. by doing U.S. Patent No. 5,539,021 described. Preferably, R ₂ : R _{1 is} in such a range that the average particle size of an average volume is less than 2 μm and the polydispersity is less than 2.

Like Pate et al. It is advantageous to prepare an emulsion having a high level of internal phase (or, if the disperse phase solidifies, a high internal phase dispersion) at which the volume: volume ratio of disperse phase to continuous Phase is at least 74/26. When water is the continuous phase, the high internal phase emulsion is advantageously diluted with water to form a stable aqueous emulsion or dispersion. Such dispersions are suitable for coating applications. When the dispersions are ionically charged, they are particularly suitable for electrophoretic coating applications.

The following examples are for illustrative purposes only and are not intended to limit the scope of this invention.

Examples 1-3 and 5 are not inventive examples.

Example 1 - Dispersion of an epoxy resin (1-type) formulation in water

The dispersion of a 1-type epoxy resin (Dow RTC 30240.22) in water was generated in a continuous hybrid disperser. The system included a twin screw extruder for melting and transferring the epoxy resin at 70 ° C as well as blending in the surfactant necessary to stabilize the dispersion. The above epoxy resin was fed to a twin-screw extruder at 25 g / min while a mixture of a surfactant was fed into the barrel of the extruder at a rate of 4.6 g / min. The surfactant consisted of a mixture of the surfactant DISPONIL ^® TA-430 (trademark of Henkel), the surfactant Atsurf ^® 108 (trademark of ICI Surfactants) and the surfactant AEROSOL ^® OT-75 (trademark of Cytec Industries) in a Weight ratio of 40/42/10. After the resin / surfactant mixture left the extruder at a rate of 29.6 g / min, it was mixed with a stream of water flowing at 75 ° C at a rate of 5 ml / min. The mixed streams were fed to an inlet of a rotor-stator disperser (ET Oakes, NY). The resulting dispersion, flowing at a rate of 34.6 g / min, was then mixed with a second stream of water flowing at a rate of 40 ml / min. The combined streams were fed to a centrifugal pump mixer to dilute the dispersion to a solids content of 40 percent. A sample was taken out and the particle size was determined to be 0.40 μm with a polydispersity (the ratio of the average particle diameter and the number of average particle diameters) of 1.17.

Example 2 - Dispersion of an epoxy resin (2-type) formulation in water

Using the equipment described in Example 1, a dispersion of an epoxy resin mixture was prepared in a continuous manner. The resin blend was a blend of 74.1 percent of a 2-type epoxy resin (Dow DER 692, equivalent 690), 24.4 percent of an epoxy / phenolic curing agent (DEH 84), 0.8 percent benzoin (Aldrich Chemical). and 0.7 percent of the flow control agent RESIFLOW ^® P67 (trademark of Estrom Chemical). The mixture was fed to the extruder at a rate of 60 g / min and combined at a rate of 26.1 g / min with a mixture of the surfactants DISPONIL TA-430 and ATSURF 108 (weight ratio 53/47). Upon exiting the extruder, the molten 100 ° C material, before being fed at 95 ° C to the inlet of the oakes dispersant, was fed at a rate of 86.1 g / min. With an initial aqueous stream of water, the at a rate of 31.4 ml / min and mixed with a stream of the surfactant AEROSOL OT-75 flowing at a rate of 2.8 ml / min mixed (so that the total velocity of the stream from the initial water stream , the surfactant stream and the molten material stream was 34.2 ml / min). After exiting the disperser, additional water was added upstream of the centrifugal mixer to dilute the dispersion to a solids content of 48 percent. The resulting dispersion had a volumetric particle size of 0.87 μm and a polydispersity of 2.6.

Example 3 - Dispersion of an epoxy / polyester hybrid resin formulation in water

Using the equipment described in Example 2, a dispersion of an epoxy resin blend was prepared in a continuous manner. The resin blend consisted of a blend of 51.3 percent of a 2-type epoxy resin (Dow DER 6224, equivalent 707) and 48.7 percent of a polyester resin (DSM, Uralac P-5598, equivalent mass 739). The mixture was fed to the extruder at a rate of 50 g / min and combined at a rate of 7.7 g / min with a mixture of the surfactants DISPONIL OT-41 and ATSURF 108 (weight ratio 53/47). The 120 ° C hot molten material exited the extruder and was fed with a stream containing water and a surfactant (prepared by mixing an initial stream of water flowing at a rate of 10 ml / min and a stream of AEROSOL surfactant OT-75 flowing at a rate of 1.5 ml / min) flowing at a rate of 11.5 ml / min. The mixed streams were then fed at 120 ° C to the inlet of an Oakes dispersant. After discharge from the disperser, additional water was added upstream of the centrifugal mixer to dilute the dispersion to a solids content of 44 percent. The resulting dispersion had a volumetric particle size of 5.8 μm and a polydispersity of 1.8.

Example 4 - Dispersion of an ethylene-acrylic acid copolymer (EAA) in polyether polyol

A dispersion of EAA Primacor ^® in the polyether polyol Voranol ^® was prepared using a continuous Hybriddispergatorsystems in which a single-screw extruder was connected to a centrifugal pump based disperser. The polymer melt exited the extruder at a rate of 10.7 g / min and at a temperature of about 130 ° C and was mixed with a stream of hot, liquid polyether polyol flowing at a rate of 35 g / min. The mixed streams were passed into a centrifugal pump to disperse the polymer in the polyol. Upon exiting the mixer, the product was collected and analyzed for particle size using a Coulter LS-230 Particle Size Analyzer. The total average volumetric particle size was 4.2 μm with a polydispersity of 6.4.

Example 5 - Dispersion of an epoxy-polyester hybrid resin formulation in water

Using the equipment described in Example 2, a dispersion of an epoxy resin mixture was prepared in a continuous manner. The resin blend consisted of a blend of 51.3 percent of a 2-type epoxy resin (Dow DER 6224, equivalent 707) and 48.7 percent of a polyester resin (DSM, Uralac P-5598, equivalent mass 739). The mixture was fed to an extruder at a rate of 50 g / min and the surfactant ADSURF 108 (2.5 g / min) was added to the extruder through a separate inlet. The extrudate of the resin material and the surfactant ADSURF 108 was fed to the disperser at a temperature of 80 ° C to 105 ° C. Meanwhile, upstream of the dispersant, the sodium salt of dodecylbenzenesulfonic acid was added to the water phase at a rate of 0.5 g / min. The water / anionic surfactant phase was transferred to the disperser at a rate of 25 g / min and mixed with the extrudate flowing at a rate of 52.5 g / min. The resulting high solids dispersion stream flowing at a rate of 77.5 g / min was further diluted in a dilution mixer with water flowing at a rate of 20 g / min to give a dispersion having a solids content of 54%. to build. The resulting dispersion had a volumetric particle size of 1.3 μm and a polydispersity of 1.5.

Claims (16)

A continuous process for producing a stable dispersion or emulsion comprising the step of mixing a stream of a molten or liquid disperse phase comprising a polymer and a stream of a molten or liquid continuous phase which is water or a polyether polyol in a mechanical dispersant to form a dispersion or an emulsion, wherein a) the continuous phase is substantially immiscible with the disperse phase, and b) the polymer is self-dispersible, and c) the polymer is extruded continuously in an extruder connected to the mechanical disperser. The method of claim 1, wherein the polymer is extruded continuously a) a Mischextrusionsverfahren, wherein other additives are mixed with the polymer, or b) a melt extrusion process. A method according to claim 2, wherein the disperse phase contains an epoxy resin, a polyester, a polyurethane resin, polyolefin or an ethylene-acrylic acid copolymer, or a mixture thereof or a hybrid thereof. The method of claim 3, wherein the disperse phase contains an epoxy resin and a curing agent and the continuous phase contains water. The process of claim 3 wherein the disperse phase comprises a polyethylene, the continuous phase comprises a polyether polyol and the polyethylene and the polyether polyol are prepared by a stabilizing amount of a surfactant prepared by reacting a maleic anhydride graft polymerized polyolefin or a maleic anhydride half ester with a monoamine polyol , are stabilized. The method of claim 3, wherein prior to mixing the stream of disperse phase with the stream of continuous phase, a catalyst and adding a curing agent to the stream of molten disperse polymer phase. The process of claim 2 wherein the continuous phase contains water and the polymer is ionically charged or contains groups that can be ionized by the presence of an acid or base in the continuous phase. The method of claim 7, wherein the polymer is ionically charged. The process of claim 7 wherein the polymer contains carboxylic acid groups and the continuous phase contains water and sufficient base to neutralize a sufficient amount of the acid groups to render the polymer electroplatable. The process of claim 7 wherein the polymer contains amine groups and the continuous phase contains water and sufficient acid to neutralize a sufficient amount of the amine groups to render the polymer electroplatable. The method of claim 7, wherein the polymer is ionically charged by carboxylate groups or quaternary ammonium salt groups or amine salt groups. The method of claim 7, further comprising the step of depositing a portion of the stable aqueous dispersion or emulsion onto an electrically conductive surface. The process of claim 1 comprising the steps of: a) continuously mixing the flow of the liquid continuous phase at a flow rate R ₁ and the flow of the liquid or molten dispersed phase at a flow rate R ₂ in the dispersant, and b) mixing the mixed streams substantially in the absence of an external surfactant and at a substantially constant mixing rate to produce, without phase inversion, an emulsion having a high level of internal phase, the liquid disperse phase stream containing a self-dispersible polymer or prepolymer and wherein R ₂ : R _{1 is} such that the average particle size of an average volume of the high internal phase emulsion is less than 2 μm or the polydispersity is less than 2. The process of claim 13, wherein the stream of liquid disperse phase contains an ethylene-acrylic acid copolymer or a neutralized salt thereof and the stream of liquid continuous phase contains a polyether polyol. The method of claim 13, wherein the liquid disperse phase stream comprises an epoxy resin, a polyester, a polyurethane, or a combination thereof, or a hybrid thereof, wherein the resins have been made self-dispersible by the chemical incorporation of ionic or nonionic hydrophilic groups. The process of claim 13, wherein the liquid disperse phase stream comprises a diisocyanate-terminated polyurethane prepolymer that has been self-dispersible by the chemical incorporation of ionic or hydrophilic groups.

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